Fasting is not all about giving up food and starving yourself. It is possible to fast by giving up any worldly thing that distracts you from God. Choosing to give up television or the internet for a period of time in order to spend more time praying is as much fasting as not eating for a period of time. The aim is not to punish yourself or suffer because of the fast, but to grow closer to God. It is about showing that we are serious about our relationship with God in that we will give up something of the world for a period of time in order to spend that time with God.
I did look into some of the rules for fasting that are used in various Christian denominations and to be honest I was surprised by what I found. There are many ways of fasting that even though you are "giving up" food you are still able to eat. For example in the Catholic tradition a partial fast allows you to have one meat meal per day and two small meals not containing meat providing the two smaller meals are not greater than the large meal. Other rules include just giving up dairy, not eating meat or only eating during the hours between sun set and sun rise. There are many different methods of fasting and this leads to a huge amount of flexibility. This flexibility come mostly from the fact that fasting is not something we have been told we must do, we have not been given guidelines to follow in this. Therefore we are able to fast in what ever way works best for us in order to commit to God and spend time in fellowship and communion with Him.
So fasting, there are no hard and fast rules. We are all aware of the time of Lent and giving something up as Jesus fasted in the wilderness. This is a kind of fasting, and some people do go to the level of giving up food and fasting for lent with caveats such as only eating plain foods or only one meal before sunrise. Whatever the method of fasting there should only be one reason to do so, in praise and honour of God, as a method of exalting Him and growing close to Him. It should not be done as a show of faith or a way of proving how good a Christian you are. Fasting is a private choice made by someone in their walk with God in order to concentrate more fully on Him.
Paul and Barnabas handpicked leaders in each church. After praying-their prayers intensified by fasting-they presented these new leaders to the Master to whom they had entrusted their lives.